THE GREAT ICE AGE 367 



with that of the beds of like age in the St. Lawrence valley, and 

 with the existing fauna of the Labrador coast and colder por- 

 tions of the Gulf and River St. Lawrence, as ascertained by 

 Prickard, Whiteaves, and the writer. It would seem that 

 throughout this region, the 60 feet and the 600 feet terraces 

 were the most important with reference to these marine 

 remains, and that their chief repository is in the Upper Leda 

 Clay, a marine deposit intermediate between the Lower and 

 Upper boulder drift, and corresponding to the interglacial beds 

 of the interior of America. 



The general conditions of the period may be thus sum- 

 marized : 



In this district, and the eastern part of North America 

 generally, it is, I think, universally admitted that the later 

 Pliocene period was one of continental elevation, and probably 

 of temperate climate. The evidence of this is too well known 

 to require re-statement here. It is also evident, from the raised 

 beaches holding marine shells, extending to elevations of 600 

 feet, and from drift boulders reaching to a far greater height, 

 that extensive submergence occurred in the middle and later 

 Pleistocene. This was the age of the beds I have named the 

 Leda clays and Saxicava sands, found at heights of 600 feet 

 above the sea in the St. Lawrence valley, nearly as far west as 

 Lake Ontario. 



It is reasonable to conclude that the till or boulder clay, 

 under the Leda clay, belongs to the earliest period of prob- 

 ably gradual subsidence, accompanied with a severe climate, 

 and with snow and glaciers on all the higher grounds, sending 

 glaciated stones into the sea. This deduction agrees with the 

 marine shells, polyzoa, and cirripedes found in the boulder 

 deposits on the lower St. Lawrence, with the unoxidized charac- 

 ter of the mass, which proves subaqueous deposition, with the 

 fact that it contains soft-boulders, which would have crumbled 

 if exposed to the air, with its limitation to the lower levels and 



